


fractionation

by pyrophane



Category: NCT (Band)
Genre: Alternate Universe - College/University, Alternate Universe - Scientists, An Emotionally Charged Multipipette Technique Lesson, Developing Feelings Over Preparative Electrophoresis Instruments, Laboratories, M/M
Language: English
Status: Completed
Published: 2019-08-21
Updated: 2019-08-21
Packaged: 2020-09-23 08:29:34
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 12,288
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20337151
Author URL: https://archiveofourown.org/users/pyrophane/pseuds/pyrophane
Summary: Mark takes up an internship at Neo Biologics for the summer and gets a whole lot more than he bargained for.





	fractionation

**Author's Note:**

> ok so this one is very different from my usual style TT i'm very nervous but i hope it's fun to read!!
> 
> anyway this is another au i've wanted to write for years but never had the motivation to do so until now(/6 months ago when i started this as a style experiment that got wildly out of control...), setting is nonspecific but probably vaguely australian. this is based off my own internship experience, though it's been a while and i am not a microbiologist, so apologies if i got any details wrong!! you shouldn't need to know anything about microbiology to read this but feel free to ask if you need anything clarified <3
> 
> title refers to the process of extracting proteins from blood

Actually it was Yukhei’s idea. Or maybe not _specifically _Yukhei’s idea, but tracing the chain of causation back far enough lands Mark at Square Yukhei, so it’s practically the same thing; Mark took Torts & Contracts as an elective first year and knows what that’s about. But anyway. They’d been chilling in a cafe on campus to take advantage of the student discount between classes and the topic of summer break, much too far away at this point in the semester, had come up. 

Mark didn’t have any plans and said so. Yukhei pulled a face. The only one of his high school friends he’d really kept in touch with after moving on to university, Yukhei somehow managed to juggle five hundred assorted extracurriculars and club activities with his studies and still have time to hang out with Mark. It was inspirational and a little scary.

“You can’t just spend the summer break sitting on your ass at home, man,” Yukhei said sagely. 

And so, armed with nothing more than a vague memory of high school biology, a one-and-a-half-year academic transcript that was probably a little more persuasive, and a CV kindly spin-doctored by Jungwoo from accounting class, he’d applied for the summer internship course at Neo Biologics after seeing an advertisement in the Career Information e-newsletter he kept forgetting to unsubscribe from, before promptly banishing it from his mind for the rest of the year, until the acceptance email landed in his inbox two days after his economics final. 

Now, waiting at the reception of the shiny white building that houses Neo Biologics’ laboratory and office spaces for someone to come out and collect him, Mark wonders what exactly had possessed him to go for an internship at a microbiology lab when he knows next to nothing about microbiology, and perhaps more importantly what exactly had possessed Neo Biologics to take him up on it. The receptionist stares unsympathetically at him like she can sense his fear. “Dr Seo will be out any moment,” she says, like a death knell. 

Mark jitters his leg, then stills it. He taps his fingers on his knee, then stills them too. A few agonising minutes later, a man bursts out from the doorway to the left of the reception desk in a swirl of white fabric and Mark jumps to his feet.

“Hey there!” Dr Seo says. Expecting a handshake, Mark sticks his hand out, only to have all the bones in his upper torso crushed to dust in a greeting hug. “Mark, right? I’m Johnny, I’ll be one of your supervisors for the course.”

“I’m Mark,” Mark says, then winces and flushes. “I mean… yeah! You just said that.”

Johnny just laughs, good-natured, and starts walking. Mark hurries to match his pace. “Nervous?”

There’s something about Johnny that instantly puts Mark at ease, so he doesn’t think too much about admitting, “Yeah, kinda.”

“Don’t be,” Johnny says. “We don’t bite!”

It's not really the teeth Mark is worried about. The lab is situated at the end of a corridor lined with offices, helpfully indicated with A4-sized pieces of paper sticky-taped to the windows reading LAB THIS WAY→. Mark isn’t sure if that means everyone in the lab is directionally challenged or if it’s some sort of welcome initiative, but he appreciates it regardless.

“So there’s me, Taeyong—” Johnny waves through the window at a pink-haired man looking despondently at his desktop; the man glances up, smiles, and waves back, though his general aura of despondence doesn’t lift an inch, “and also Yuta but he isn’t in the office today. Everyone kind of comes and goes but you’ll get to know the whole lab eventually.” 

“Awesome,” Mark says. 

The hallway opens out into a foyer-like area kitted out with a sink, a huge showerhead hanging down from the ceiling, a row of lab coats hanging from hooks, and an array of glasses. 

“This line,” Johnny says, pointing at the thick black line stretching from wall to wall painted on the floor between the red linoleum and the white tile, “is where the lab starts. You don’t cross that line without a lab coat and safety glasses on, and once you’re on the other side they don’t come off. We take safety very seriously here.”

“Of course,” Mark says. He knows a prompt when he sees one, takes a lab coat from the rack and a pair of safety glasses and dons both articles. 

He steps over the line and into the lab, but Johnny doesn’t join him. 

“Normally I’d show you around the lab, but I’ve got an investor meeting to run to very soon,” Johnny says, sounding genuinely regretful. “So I’m gonna pass over to one of your project partners—really sorry about this, but I promise you’re in good hands. Learn by doing and all that! Hey, Donghyuck!” 

A boy materialises in the gap between two benches, cradling an enormous empty flask in his arms, his face blurred and distorted through the curved glass. The flask has got to be at least the size of his torso. Mark stares, but Johnny doesn’t bat an eyelid, so he guesses this is just par for the course in the lab.

“New intern?” the boy asks, setting the flask down on the bench, and Mark sees him clearly for the first time. _Round_, is the prevailing impression. Round face, big round eyes. Heart-shaped mouth, double the roundness. 

“Yes, so play nice,” Johnny says. He turns to Mark. “This is Donghyuck, it’s his second year with us, so he knows what he’s doing. Mostly.”

“Hey!” Donghyuck yelps. Johnny laughs good-naturedly and ruffles Donghyuck’s hair. “I know one hundred percent of everything, just so we’re clear on that,” he says to Mark.

“I’m Mark,” he says. “Lee,” he adds, as a slightly awkward afterthought.

“Lovely to meet you,” Donghyuck says. He has the brightest eyes Mark has ever seen on any human being, and Yukhei has an impressively sparkly set.

“Okay, I gotta go,” Johnny says, glancing at his watch. “Hyuck, can you finish showing Mark around? I’ll get him started on the Gradiflow tomorrow, so don’t worry about that, just introduce him to the project.” 

Johnny’s barely out of the door before Donghyuck starts talking. “So did Johnny tell you anything about the project yet?” Mark shakes his head no. “We are,” Donghyuck inhales grandly, “optimising buffer conditions for the separation of Immunoglobulin-G from human blood plasma. Still working on a catchier title, though.”

“Immuno…” With a vaguely sinking feeling Mark realises Donghyuck doesn’t know that he’s a stranger to the whole microbiology thing. He should probably tell Donghyuck before he gets too hopelessly confused or is required to weigh in on any substantive point of scientific expertise, but he has no idea how to broach the subject without embarrassing himself.

“Oh, you know.” Mark almost certainly does not know whatever Donghyuck is about to say next. “It’s an antibody. IgG for short, maybe you’ve heard of it like that.” Mark hasn’t. Donghyuck leads Mark over to a row of machines kitted out in white and teal plastic. “I think it’s used in therapeutics for autoimmune disorders? Anyway, it’s important ‘cause the buffer normally used in the fractionation process is really expensive, so if we can test good results out of a cheaper buffer then the treatment will be a lot more affordable.”

“That’s... good,” Mark says. Financial considerations are definitely more of a familiar territory. “Affordable is, um, good.”

Rather kindly, Donghyuck does not let on whether or not he’s fazed by the quality of Mark’s commentary. “And these babies are our Gradiflows,” Donghyuck says, gently resting a reverent hand atop the translucent teal lid of one of the machines. “Plasma and buffer goes in one stream, just buffer in the other, then the Gradiflow does all the work getting the IgG for us. We get size _and_ charge-based molecular separation out of them.” 

This sounds very impressive and Mark does his best to appear suitably awed. However, Donghyuck is essentially speaking another language; Mark finally opens his mouth to request a translation but Donghyuck’s already steamrolling ahead, and Mark resigns himself to asking Johnny for some readings on the topic later. 

“Each cycle is half an hour long, and we run twelve of them per trial,” Donghyuck continues, leading Mark to the next bench down, which houses yet another row of boxy machines. “So each set of data takes six hours to collect, plus analysis. It’s a lot of waiting,” he admits. “But, hey, we get the lab to ourselves!” 

“Neo Biologics has so much faith in the ability of university students to not blow up their expensive equipment, huh,” Mark says, peering more closely at the display of the nearest machine. Handily, it’s been labelled _CENTRIFUGE_, which solves that particular mystery. To be fair, the Gradiflows had also been labelled _GRADIFLOW_, but it was less helpful when he hadn’t actually known what a Gradiflow was in the first place.

“I mean, they’re usually just in the office next door, so if anything happens they’ll be right there,” Donghyuck says. “But really, there’s nothing to worry about! This is the easiest project _ever_, trust me. Or trust Johnny. I know what I’m doing, you heard it from him.”

“I won’t lie, that kind of sounds suspicious,” Mark says, unable to keep the smile from his face. “But I’ll take your word for it.”

“A quick learner,” Donghyuck says approvingly. He keeps moving, and Mark follows. “Not like those commerce majors, am I right? People always go on about STEM versus arts or whatever but the real enemy is the business school. The other day I had a lecture in the business faculty building and the class before mine was like, _risk is bad_ or something, and I was like, I cannot believe this is a real degree.”

Mark winces. Valiantly, he redirects. “So…” Mark says. “Are there any other people in our project team?”

“There's Renjun? He’s got some mooting competition on today, the traitor. Finals. He’s really good.” Donghyuck delivers this last statement with a weird combination of hostility and fierce pride. “So it’s just us two in the lab for now. Should be fun!”

It certainly will be something, that’s for sure. Despite the minimal physical exertion required to do a lap of the lab, Mark feels winded. Something about how easy it is getting swept along with Donghyuck’s vibrant pace and he doesn’t have the space to breathe. “Mooting?” Mark says.

“Yeah, Renjun double-majors in law and med science. For some reason everyone else here does med science? So they all already know each other… nepotism at its finest.” Donghyuck pauses, wrinkling his nose. “I’m surrounded by double-majoring overachievers. And also the only actual microbiologist here. So what’s your field, anyway? Pathology? Biochem? Med science like every other person in this lab?” 

And there’s his chance, though it’s not very opportune. “Haha, actually…” Mark grins, sheepish. “I’m a finance major.”

There’s a long beat of silence. Donghyuck stares at him. “You’re a _what._”

“Finance major,” Mark repeats obligingly.

“You’re telling me _now?_ After I just spent like ten minutes talking shit about business students?”

“You were really getting into it!” Mark says. “I didn’t want to, like, interrupt your flow or anything.” Donghyuck’s cheeks pink. On impulse, Mark adds, “Plus, it was kinda cute.”

“Oh my god,” Donghyuck says, swivelling around with an exaggerated flourish like he’s addressing an imaginary camera. It affords Mark a great view of the flush sweeping across the back of Donghyuck’s neck before he completes a 360 and faces Mark again. “Well, for the record I was mostly talking about Jaemin, the economics bastard. And you’re not double majoring or anything?” Mark shakes his head. “Then, like… no offense, but what are you doing in a microbiology lab?”

So the thing is, as a finance major, Mark does a decent amount of bullshitting business theory about SWOT or TBL or whatever, and he’s pretty good at it even without Jungwoo’s help, if his grades are anything to go by. But faced with the curiosity on Donghyuck’s face keen as a blade he can’t remember a single one of the justifications he’d submitted in his internship application.

“Honestly?” Mark blurts out. “I thought it looked cool.”

Donghyuck’s eyes narrow, nearly slow-motion. “Okay,” he says, dragging the syllables out. “Well, so long as you take it seriously, because I’m not gonna do your work for you.”

“I take all my work seriously!” Mark insists, feeling vaguely offended even though he’s given Donghyuck no reason to trust him in the first place. But if there’s anything he takes pride in it’s his work ethic, and he knows he can prove himself on this front. 

For a moment Donghyuck is scrutinising him with x-ray intensity, and then the expression clears, Donghyuck apparently being satisfied by whatever he’s divined out of Mark’s face. “I’m watching you, Mark Lee,” he says, but there’s levity to the words now. It feels like a victory. Mark grins.

The tour continues. “We’re actually sharing labspace with another company because rent is apparently a bitch.” Donghyuck says, coming to a stop right up against a line of black electrical tape running across the length of the floor, midway between two benches. “So _that_ half of the lab belongs to Culture Biotechnology, I’m not exactly sure what they’re working on but it involves a lot of petri dishes, which is kinda cool, and also they’re never in the lab for some reason? But be glad you’re interning with us and not them.”

Mark pauses in the middle of dutifully trying to absorb everything Donghyuck is firing off. “How come?”

Donghyuck sighs, a vigorously gusty exhale any pining Victorian maiden would be proud of. “It’s a long story.”

“Well,” Mark says, pulling one of the stools out from under the bench and narrowly saving himself from sliding right off it again when he finds out upon contact that it’s one of those ones that spin. “I’ve got time.”

Donghyuck’s eyes glitter as he mirrors Mark except with significantly more grace, dropping onto another stool opposite him. “So, basically, there was this beaker full of those old-fashioned plastic pipettes on their half of the middle bench we share. You know, the ones that look like eye droppers—_do_ you know?”

“I did take high school science,” Mark says dryly. “Like, it was compulsory. And I do also know what an eye dropper is.” 

“_Okay_, just checking, Mr The-Market’s-Absolutely-Fully-Capable-Of… whatever the hell finance is about. Anyway, so I was like, well, I haven’t seen one of those for _decades_, ‘cause Neo Biologics really splurged on the lab equipment, so I went to pick one up. And then _that_ guy fucking, like, divebombed me like a vulture. Something about _contaminating sterile instruments_ and _tell Taeyong to mind his own business_. But if he didn’t want people to touch it maybe he shouldn’t have left it out on the bench?” Donghyuck somehow manages to tilt his stool back contemplatively without falling off it. “The supervisors at Culture Biotech are crazy scary. Plus they make their interns work really hard, Jisung always looks mad stressed. Though maybe that’s just his face. Best to stay on this side of the lab.”

Personally, Mark would not have elected to touch the equipment in the first place no matter how temptingly antique, but maybe that’s just him. “Uh,” he says, unsure of how exactly to respond to this anecdote. “That’s… intense?”

“I know right? But what can I say…” Donghyuck spreads his arms, theatrical. On anyone else the gesture would look pretty ridiculous; on Donghyuck it just seems apt. “Welcome to Neo Biologics.”

Nobody in the lab runs on the same schedule. By the time Mark arrives the next day, as planned, the lab is empty, and again Johnny’s the only person there to greet him. Johnny shows him how to set the Gradiflow up, the two plastic ducts feeding in and out of a pair of graduated tubes, some complicated filtration system inside the machine that sieves out the protein they’re looking for from the first tube and dumps it in the second tube. Mark tried to read some of the papers Johnny emailed him last night on the whole process, but the academia of it all made his head swim. The most taxing texts he’s had to read and write over the past year or so have been business reports, and there’s only so many five-syllable _-ion_ words he can process in a row before he starts losing patience no matter how determined he is to push through. 

But Neo Biologics are otherwise incredibly considerate of his total lack of experience, which cements Mark’s belief that nobody else applied for the internship. It’s a trial run today to ease him into the lab routine, only three hours instead of six. 

He meets Renjun when a boy balancing an empty watercooler-sized flask in his arms—so carrying around large glassware _is_ the norm here—pauses a bench away from the Gradiflows, and says, warily, “Hi?”

“Hi!” Mark says. “I’m the uh, new intern. Mark Lee.” He puts his hand out.

The boy eyes Mark’s proffered hand, eyes the flask taking up all of his available armspace, and pointedly sets the flask down on the bench before shaking Mark’s hand. Mark could probably melt a hole through the floor out of shame.

“Renjun Huang,” he says. “Donghyuck told me all about you.”

Mark isn't sure if he's hallucinating the vaguely threatening undertone to the words. “What did he say?” Mark asks, trying not to sound nervous.

Renjun smiles. “You can ask him yourself,” he says, pointing at the entrance, where Donghyuck is throwing on a lab coat.

Mark is not going to do that. “Did you miss me?" Donghyuck calls. He disappears from view for a few moments, then reappears carrying a huge flask identical to the one Renjun is hovering over. 

“No,” Renjun says. “Reply to my texts.”

“_You_ reply to _mine_ first,” Donghyuck retorts. 

“What’s the deal with all the giant beakers?” Mark asks.

“Mixing buffer for the Gradiflows,” Renjun says. He points to some labelled bottles of more clear liquid on the bench: _histidine, MES, BIS-TRIS_. “We like to do it ourselves so we get the ratios right.”

Mark assumes he’ll have to do this tomorrow too, so he conscientiously watches the two of them elbow each other out of the way at the pure water station (Renjun wins), then again in front of the chemical bottles (Donghyuck wins). The look on Renjun’s face grows steadily darker as Donghyuck proceeds to use up the entirety of one of the bottles, and without a word he gets up from his seat and vanishes through the door to the back room.

“He’s a pain, isn’t he,” Donghyuck says. His words are at complete odds with the affection saturating them. Not for the first time, Mark wonders what’s supposed to be going on there.

“I don’t think he likes me very much,” Mark admits under his breath.

“Don’t worry about it, that’s just how he is. Renjun doesn’t like anyone,” Donghyuck says cheerfully. “Except maybe Sicheng? He’s one of the supervisors on Jaemin and Jeno’s project, but only sometimes. Oh, also Dr Wen from the astrophysics lab on the second floor. So unless you’re a hot older Chinese guy with a PhD you’re out of luck.” 

“Great,” Mark sighs. 

Mark gets to meet the rest of the Neo Biologics team other than the mysterious Sicheng when they’re all congregated in Taeyong’s office for a briefing after lunch. As it happens Taeyong is just wired to look devastatingly sad even when he isn’t actually, which is something Mark will have to adjust to. Yuta is scary in a way Mark can’t quite put his finger on, despite—or because of?—the smile that flickers across his face at irregular intervals, and Johnny is, thankfully, just Johnny. 

Donghyuck introduces him to Jaemin and Jeno from the other intern project, and while Jeno’s warm right from the get-go, there’s something reserved, almost assessing, underneath Jaemin’s effortlessly friendly charm. Mark doesn’t think he’s supposed to pick up on it, and also doesn’t know what to do about it, so he pretends not to have noticed.

So overall that gives a count of three people he’s comfortable with, three people he’s vaguely unsettled by, and one Donghyuck. Mark hasn’t figured out how to categorise him just yet. It’s not a bad ratio, all things considered. And having things to work on is good, keeps him on his toes, keeps him looking forward. That’s why he’d come here in the first place, right? Maybe he’s exactly where he needs to be.

As it turns out Donghyuck wasn’t kidding about the waiting. There is _so much_ waiting. Since they haven’t collected enough data to start any analytical process yet, there’s nothing to do during the course of the half-hour cycles. They’re not long enough to leave the lab and do something in between, but they’re not short enough to feel anything less than agonisingly endless, minutes oozing by like toxic sludge. 

“Let’s talk,” Donghyuck says grandly, once everyone’s Gradiflows are going, “about—”

“No,” Renjun interjects.

“—love!”

“_No,_” Renjun repeats, more emphatically.

Jaemin steeples his hands under his chin. “That’s not what you were saying last—” Renjun lunges forward, effectively cutting off the rest of the sentence along with Jaemin’s airway. For a few moments Jeno regards this scene with the vaguely fond air of someone watching their pet cats squabble before gently prying Renjun’s hands off Jaemin’s neck.

“Mark, you start,” Donghyuck says, thumping Jaemin on the back in what seems like an entirely unhelpful move that only makes Jaemin splutter more. 

“This is a bit, um, deep for ten in the morning,” Mark says.

“Well, it’s either this or word games,” Jaemin says cheerfully, recovering in an instant. “You know, like, I Spy, and whatever that thing is called when you have a topic and you have to say a word that starts with the last letter of the word the person before you said.” He leans forward, a grin verging on diabolical stretching his mouth wider than Mark had thought humanly possible. “But isn’t this a good way to get to know each other? Laying bare your deepest, darkest secrets—”

“Do you guys not have games on your phones or something?” Mark asks. Maybe it’s a STEM thing. He needs to tread carefully here.

Jeno points to a sign over the pure water dispenser that reads NO PHONES!!!!!! in massive red block letters, accompanied by a stylishly rendered drawing of some kind of many-limbed many-eyed many-toothed creature crunching a giant mobile phone in half. 

“... Right,” Mark says. “Not sure how I missed that the first two days I was here.”

“Renjun drew the picture,” Jeno says proudly. 

“I did,” Renjun affirms.

“Our Injunnie is so creative,” Jaemin coos, scrunching his face up goblinly and reaching for Renjun.

“Can someone call Jisung over, I think Jaemin is going through withdrawals,” Renjun says, fending Jaemin off with expert nonchalance. 

Mark glances at Donghyuck in desperation, searching for some semblance of normalcy or at least familiarity as the person he’s known longest out of this group, which is not really saying that much, but there’s no rescue to be found there. Donghyuck just gazes tenderly at Renjun in the manner usually reserved for cute baby animals and a bride being unveiled on her wedding day and the like. Mark doesn't realise he's frowning until Jeno pokes him in the forehead.

Partly to deflect, Mark mutters under his breath to Jeno, “Are things always like this?” Without any apparent cue or indication, Jaemin and Donghyuck have swapped roles so that now Renjun is pretending(? Mark hopes) to throw a chair at Donghyuck while Jaemin stares at Renjun with what can only be described as all-consuming adoration.

“Oh, yeah,” Jeno says, eyes crinkling up pleasantly. “We never get past the first hour in the lab without Renjun trying to kill or maim someone. But don’t worry, we’re really big on lab safety here!”

Somehow this is not reassuring at all. Honestly the main reason Mark hasn’t run out of the lab screaming is that he’s more than a little intimidated by the lengthy washup process required to safely and ethically leave the lab. Why does Neo Biologics have a procedure more complicated than his sister's ten-step skincare routine for washing your hands but no protocols to prevent attempted intern-on-intern murder? 

“Guys,” Mark says, feeling a duty to intervene. “Guys,” he repeats, more loudly. Renjun graciously pauses in the middle of trying to tip Donghyuck’s chair over. "Maybe, uh… don't do that next to the Gradiflows.”

"Well, if you insist,” Donghyuck says, sighing, but they both oblige. 

Afterwards, one of the hot older Chinese men with PhDs Renjun is allegedly in love with comes in, offering Mark a slight smile and introducing himself as Sicheng, and Jaemin and Jeno move to a different bench with him.

Mark peers at the steady drip of fluid into the rightmost tube docked into his Gradiflow. “It’s kind of... pink,” he says. The longer he looks the more distinct the peachy tinge to the collecting protein-buffer mixture becomes. “Is it supposed to be pink?”

“Mine’s clear,” Renjun says. 

“You have the control run, of course it’s clear,” Donghyuck says. “This isn’t about you.”

Renjun rolls his eyes. “Maybe it’s not the extra histidine in his buffer, did you ever think about that? Maybe it’s another variable. Maybe it’s the machine.”

“Whatever,” Donghyuck says. He turns back to Mark. “Anyway, this is good! This is the kind of stuff you can talk about in the writeup.” 

Truthfully Mark had forgotten there was a written component to the project. “I don’t know what it means, though?”

“That’s for the hags to figure out,” Donghyuck says sunnily. 

Mark chokes. “Do they know you call them that?”

“If they don’t then they should,” Donghyuck says. He waves the thermometer that’s somehow appeared in his hand between the last time Mark looked at him and now. It takes Mark a moment to realise he’s offering it to him.

Dutifully, Mark takes a temperature reading from the collecting tube in his Gradiflow, records it in his journal and passes the thermometer back to Donghyuck, who goes to dunk it directly into his machine.

“Hang on,” Mark says sharply. “You’re not gonna clean it first? Isn’t that, like, cross-contamination or something?”

“Huh,” Donghyuck says thoughtfully, inspecting the damp thermometer bulb.

Renjun frowns. “You’re right,” he says. “Should we ask?”

So they flag down Sicheng at the other bench who flags down Yuta, who basically shrugs and says it doesn’t really matter, but Renjun gets a paper towel from the sink and does a cursory clean of the thermometer anyway before taking a reading from his machine.

“Hey,” Donghyuck says, staring pensively at his buffer pool, “do you think mine is getting kinda pink too?”

“What, so this isn’t about _me_ but it can be about _you_?” Renjun says.

“Of course,” Donghyuck says. “It’s always about me.”

“Yours doesn’t look pink to me,” Mark tells him. 

“Thank you,” Renjun says.

They start taking samples from their collecting streams. Apropos of literally nothing, and heedless of the fact that the subject of his gossip is just two benches down, Donghyuck snaps his fingers and says, “Oh, that reminds me—Renjun, you remember Jieqiong, right, Sicheng’s girlfriend? Why am I asking, you know everything related to Sicheng. Anyway, apparently she went to see a fortune teller and changed her English name.”

Renjun finishes scribbling the date and cycle number onto the top of the microfuge tube in his hands and caps the marker pen with a decisive click. “What was it before.... Pinky?”

“Yeah, and now it’s Rainy, because the fortune teller told her she lacks the water element in her life or whatever.”

“Hey,” Mark says. “Hey, so if I lack the cash element, then I should change my name to Money?”

There is a pointed beat of silence. “And people have the nerve to call _me_ unfunny,” Renjun says, directed to the ceiling, so he’s either addressing God or Dr Wen on the second floor.

“It wasn’t that bad,” Mark protests. “It was pretty good, come on.”

Donghyuck dumps the contents of the tube he’s holding into the pooled protein-buffer mixture in a measuring cylinder and replaces the empty tube in the Gradiflow to start the next cycle. “Moving on,” he announces, but he’s interrupted by a series of metallic screeching noises followed by the distinct tenor of human voices, the words themselves unclear but the tone of alarm immediately recognisable.

Renjun pauses and tilts his head, narrowing his eyes. “What the hell is going on out there?” 

The commotion turns out to be from someone trying to drag tables out for an interfloor communal lunch event that Mark wasn’t aware of, and judging by the general shimmer of confusion across the lab neither was anyone from the Neo Biologics contingent. Taeyong saves the day with a hurriedly-placed phone call for pizza delivery, and Mark finally gets to meet the infamous Culture Biotechnology crowd, or rather their allegedly unfortunate intern team Chenle and Jisung, who don’t seem to be faring that badly. Chenle swoops in to pinch Mark’s cheeks within seconds of introduction like a fussy auntie three times his age. He proceeds to coo something about how cute Mark is, solidifying the impression. 

Everyone from the astrophysics lab upstairs is terrifyingly well-proportioned, face-wise, including their interns, which makes Mark wonder if that’s one of the criteria they canvass applications on. The infamous Dr Wen, or Just-Call-Me-Junhui!!! complete with the three audible exclamation marks, is chatting to Taeyong and Renjun next to the drinks table after doing the requisite round of introductions, and Mark won’t lie, he did fall briefly in love too the moment Dr Wen locked eyes with him and flashed a brilliant trapezoidal smile. 

Mark is half-listening in on Johnny congratulating two of Dr Wen’s coworkers on their engagement when Donghyuck sidles up to him, plastic cup of coke in hand. Mark doesn’t like coke, which he remembered halfway through pouring himself a cup, so he's been discreetly looking for somewhere to dispose of it for a while now, and the fake potted plant in the corner is looking increasingly attractive as an option. 

Donghyuck tips the entirety of his drink into his mouth. He’s standing next to Mark, but he’s looking thoughtfully at Renjun flutter his eyelashes up at Dr Wen.

“Hey,” Mark says. “So are you and Renjun, like…”

“Like?”

Mark drops his voice to a whisper. “Like, you know… a thing?”

Donghyuck gives him a look like Mark is the weird one for being confused about the parameters of his frankly mystifying relationship with Renjun. “What kind of thing? Sure, we have an app that counts how many days it’s been since we met, but who doesn’t in this economy?” He flashes his phone screen at Mark, and Mark catches a brief glimpse of _In Hate 379 Days♡ _emblazoned across the middle before Donghyuck stows his phone away again. “Why do you ask?”

Carefully, Mark elects to ignore the strange sense of relief that bubbles up. “No reason,” Mark says. “Just curious.”

Donghyuck fixes Mark with a harrowing stare. “Okay, but as Renjun’s best friendival… frival…”

“Frenemy?” Mark suggests.

“_Frenemy_, whatever, I have a responsibility to make sure your intentions towards him are honourable. So declare them now.” He frames his face with his hands, expectant.

“Um,” Mark says. “I think that Renjun is… very…” _Scary_, his brain supplies unhelpfully. “Nice,” he finishes. “But I’m not, like, uh… looking to date him?” He’s not sure if he should be apologising for that. 

“You aren’t? And why not.” 

Exasperated, Mark says, “Do you want me to be interested in him or not?”

This actually seems to throw Donghyuck for a loop. His eyes narrow. He looks almost like he’s on the verge of an existential crisis before he blinks and his expression clears. 

“So you _are_ interested?”

“Did you hear a single word I just said?”

“Nope,” Donghyuck says brightly. 

Mark fights the urge to scream. While he’s occupied with that, Donghyuck plucks the cup from Mark’s hand, replacing it with his own empty one, and downs the remainder of Mark's drink before Mark can redirect the necessary neurons to protest. “You’re lucky you're so—”

He snaps his mouth shut, but it’s too late: the damage is done. “Cute? Endlessly lovable?” Donghyuck suggests, leaning closer and closer until Mark’s eyes are almost crossing with the effort of focusing on him without backing away. “What were you going to say? Ooh, is it _me_ you’re interested in? Do you _like_ me, Mark Lee?”

Mark splutters. “What the—no? I—You stole my drink!”

“Well, you weren’t drinking it,” Donghyuck points out.

He’s right, but Mark isn’t going to let him win that easily. “You don’t know that.”

“Sure I do,” Donghyuck says. “You’ve been trying to get rid of your cup for the past ten minutes but you didn’t want to put it back down on the table with the unused cups. Very upstanding citizen of you.”

Mark is—touched? Annoyed? Scared? He’d had to pass a core unit on emotional intelligence as part of his finance major requirements and he’d come out the other end of it no less bewildered about the apparently complex process of just knowing what the hell he was feeling, let alone any of the higher tiers of emotional competency. The point is that Donghyuck was looking closely enough to notice—wait, no, the point is that Donghyuck put his mouth where Mark’s had been seconds ago and looked him straight in the eye as he did it. What is that supposed to mean? 

Donghyuck pulls back. Mark blinks. The moment fizzes out, leaving an aftertaste in Mark's mouth that's almost corrosively sweet. He takes his empty cup back from Donghyuck and stacks it on top of the one he's holding. “Well,” Mark says. “Thanks, then.”

Eventually everyone gets bored enough to start playing word games in earnest. “Someone give a topic, quick,” Jaemin says.

“Colours?” Jeno suggests.

"Boring," Renjun complains.

“That’s not fair,” Donghyuck grumbles. “Renjun has an advantage.”

“Excellent, let’s go with that one,” Renjun says.

Donghyuck is summarily outvoted, since Jaemin sides with Renjun and Jeno was the one who came up with the topic in the first place and Mark abstains out of self-preservation. He’s still got more than a month left in this course and he’d rather not make an enemy out of either Donghyuck or Renjun, in the interests of remaining alive by the end of it. Meanwhile Renjun takes advantage of the mobile phone ban to try and convince them that _keryllion_ is a real colour after Jeno catapulted _ebony black_ into the game off the end of Jaemin’s _blue_ and stalled them all. 

“Now I may not be a colour expert,” Donghyuck is saying, “but I don’t think that’s a real one.”

“Yes it is,” Renjun insists. “It’s a type of red, I’ve used it before. I’m the artist here, I know what I’m talking about.”

“Wait a minute,” Jeno says. “Isn’t that _vermillion_.”

“No, that’s a different shade of red,” Renjun says. “It’s really bright. Orangey kind of red. Keryllion is darker.”

“That doesn’t sound right,” Mark says slowly, “but I don’t know enough about colours to argue.”

Renjun’s poker face doesn’t slip an inch. “I _do_ know enough about colours to argue. And what you should be thinking about is what colours start with _n_, because it’s your turn now.”

Predictably, Renjun wins the round and is promptly disqualified from the next by unanimous vote on suspicion of cheating, though he maintains his innocence with a wide-eyed guilelessness that nobody, Mark included, buys. Jaemin does waver a little but holds firm in the end.

When they break for lunch Jeno and Renjun hang back by the coat rack. Jeno leans down to whisper something in Renjun's ear. Renjun swats Jeno on the upper arm before hooking his hand through the crook of Jeno’s elbow and tugging him out of the door.

“Where are they going?” Mark asks.

“Rooftop, probably,” Donghyuck says.

“You can access the rooftop?” Mark frowns. “That seems… kind of unsafe?”

“There’s no point telling Renjun what he can or can’t do,” Jaemin says.

“See, that’s your problem, you don’t know how to handle him at all,” Donghyuck says. “You can’t just _give in_ every time he does his picky cat routine. Then he’ll drag you off to the rooftop during your lunch break to make you talk about your feelings, full, like, Socratic method interrogation style, and then you’ll both end up crying on the daily.”

“Well, you know what they say,” Jaemin sighs. “Happy wife, happy life… or something like that.”

Donghyuck snickers. “You married Renjun? My condolences.” 

“I hear the tax benefits are pretty good,” Jaemin says contemplatively. “Wish they stacked… I could just marry everyone and watch the reimbursements flow in…”

“I don’t marry before a first date,” Donghyuck says. “Let’s get that clear. Buy me dinner and then we’ll talk.”

“I’m uninviting you from my future wedding to Jeno, just so you know now,” Jaemin says.

“You can’t do that,” Donghyuck informs him loftily. “I’m going to be Jeno’s best man of honour or whatever it’s called, my rights to be there are unalienable. And then I’m going to move into your marital residence. I’ll be the first thing you see when you wake up every morning. You won’t be able to get rid of me.”

“Great, so I’m basically marrying you as well, except without any of the benefits.”

“I _am_ the benefit,” Donghyuck retorts.

Mark, watching this rapid back-and-forth unfold like an umpire at a tennis match, offers, “Shouldn’t you only marry someone you’re in love with?”

“You can take that up with Injunnie,” Jaemin says. “He’s a firm romantic at heart. Very deep down, somewhere very deep down in his heart. Actually not that deep down but the number one key to staying alive through the course of a friendship with Renjun Huang is letting him pretend he doesn’t have feelings, even though he clearly does. Consider this free advice as a show of goodwill from me to you.”

“... Thanks?” Mark says. He hadn’t intended it to come out as a question but it does anyway, which is the manner in which most things that happen to him in the lab occur.

“You’re welcome,” Jaemin says magnanimously. 

Most of Mark’s time in the lab is spent in peaceful coexistence with Johnny and Yuta working on their own research a couple benches down, as well as Chenle and Jisung across the electrical tape barrier emitting a perhaps worrying quantity of muffled shrieks and giggles from behind the fume hood, but that’s their harried-looking supervisor’s problem and not Mark’s; and distinctly non-peaceful coexistence with the rest of the Neo Biologics intern fleet. 

So far everyone else at Neo Biologics seems to conduct themselves like they’re the protagonist of a tragic Shakespearian drama. Not that Mark, who spent the bulk of his high school English classes discreetly messaging Yukhei and only wrapped his head around the bare minimum of Shakespeare needed to sufficiently thesisise and scrape some decent grades, knows much about what that entails. But just days ago Renjun and Jaemin playacted a mock swordfight in front of Yuta’s office, culminating in both of them simultaneously pretending to stab the other in the stomach, while Donghyuck loudly critiqued the anatomical accuracy of their death throes, so he thinks the comparison is justified. It’s a lot to take in.

Taeyong drops by to show Mark how to do the proper serial dilutions with a micropipette so they can start the analysis stage of the experiment. He seems less sad and strung-out lately, which is a relief, because it’s been kind of looking like he’s just about ready to shatter on impact. Coupled with Donghyuck’s offhand comments about rent and potentially reckless inventory spending when they met Mark really hopes Neo Biologics’ financials are all problem-free.

Mark lifts one of the microfuge tubes up to eye-level to inspect the diluted sample. He taps the side with his index finger. “There’s an air bubble in this,” he says. “Is that, like, bad?”

“Yes,” Renjun says, and declines to comment further.

“Centrifuge it for a bit,” Donghyuck suggests.

The row of centrifuges on the opposite bench loom up at him like tombstones. “Um,” Mark says. “Are we allowed to?”

“Sure,” Donghyuck says. “Just pop it in there on a low-ish setting for twenty seconds or so.”

Renjun doesn’t contradict him on this point, so Mark trusts that at the very least the tube isn’t going to come flying out of the centrifuge and take someone’s eye out. On the other hand, it’s equally as likely that Renjun’s done some quick maths in his head and figured that any resulting projectile is on the right trajectory to take _Donghyuck’s_ eye out, which is why he hasn’t spoken up. Mark has a startlingly lucid vision of Donghyuck with an eyepatch like a pirate, a parrot perched on his shoulder feathered the same bright pink as Jaemin’s hair.

It would be a shame if Donghyuck lost an eye. Mark slides the tube into the centrifuge and shuts the lid alongside this train of thought with the finality of lowering a coffin into a grave. He presses the start button and—nothing happens. He waits. He presses the start button again. 

“Usually it helps if you turn the mains power on,” Renjun says.

“Right,” Mark says, nodding to stave off the embarrassment looming over the mental horizon. He tries to trace the centrifuge cord through the maze of wires back to a wall socket, but Renjun beats him to it, reaching over to flick the switch.

“I’m the one who lights up the world,” Renjun says, as the centrifuge powers up, LED display blinking on. “You’re welcome.”

“Uh,” Mark says. “Thanks.” 

He presses the start button again and lets the centrifuge run. When he takes the tubes out again and holds them up to the light the results aren’t perfect.

“There’s still a little air bubble in this one,” Mark says.

“Just leave it, that’s as good as it’ll get,” Donghyuck says. Mark frowns and puts the tubes back in for another spin. There’s this one tiny stubborn bubble that refuses to pop and eventually he has to admit defeat.

But that’s not the last of the air bubble trials. Under Johnny’s watchful gaze, they dye and load the diluted samples into multipipettes so they can measure the protein concentrations with a Bradford assay. If Mark thought pushing a button to dispense some liquid into some holes would be an easy task he’d be dead wrong. Donghyuck does his flawlessly in about three seconds flat before Mark’s even figured out how to get the plastic tips onto the multipipette properly, his microplate wells beautiful flat circles of deep blue, but Renjun on the other hand falters for the first time since Mark’s known him.

“I hate this part,” Renjun mutters. He glares at his microplate, studded with air bubbles, with such sizzling fury Mark wouldn’t be surprised if the protein samples all denatured on the spot. 

“It’s okay,” Donghyuck says. “We can’t all be as naturally gifted with the multipipette as I am.”

Taking a clean pipette tip, Renjun starts stabbing at the bubbles in the microplate wells and doesn’t deign this with a response. The fact that Renjun, whose lab techniques are otherwise scrupulously faultless when he isn't attempting to inflict grievous bodily harm on someone, can’t pipette properly does not bode well for Mark’s first try.

Donghyuck must pick up on Mark’s hesitation, because he rounds the corner of the lab bench to Mark’s side and says, “Here, I’ll show you.” Instead of taking the multipipette from him, he wraps his fingers around Mark’s hand, guiding it so the pipette tips align with the first row of microplate wells. “The trick is to push the tips right up against the edges of the wells,” he explains. His thumb brushes over the back of Mark’s hand on its way to the plunger button. “There’s two stops, you have to make sure you’ve already pressed the button down to the first one to like, push the air out or something, I don’t know. Feel how there’s a bit of resistance halfway down?” Mark nods. “That’s the first stop. Then you press down the whole way. Evenly, but not too quickly.”

Under Donghyuck’s fingers, the liquid flows out of the pipette tips, little spheres of blue expanding to fill the wells perfectly. Not a single air bubble to be seen.

“Wow,” Mark says, without thinking it through. “You’re really good.”

Donghyuck stares, like he’s taken aback by the words. When he removes his hands from Mark’s, slow, Mark’s skin flashes warm, then cool, then warm again. “Now you try,” Donghyuck says.

The next step is fitting the data to a standard curve. The microplates are scanned with a reader, the protein quantities in each well plotted on some graphing software. The details of the spectroscopy might be beyond him, but the sight of Excel is comfortingly familiar. Mark's taken a statistics course, so this part is something he actually already knows how to do, which is an exciting turn of events in his Neo Biologics experience. 

“R-squared, r-squared,” Renjun chants. “Hurry up, get the reading out!”

“You’re gonna lose anyway, I can beat 0.92 pipetting with my left hand and my eyes closed,” Donghyuck scoffs, clicking around in the graph display options. “Ha! See? 0.98. You could never.”

Renjun scowls. “We’ll see about _that_.”

“Guys, it’s really not a competition,” Mark says. “We’re on the same team...”

“Sounds like something a loser would say,” Donghyuck says. “And I like to _win._”

“Everything is a competition if you aren’t a coward,” Renjun says. 

“Are you a coward, Mark Lee?”

“I—no? I don’t think I am?”

“Good,” Donghyuck says, gesturing at the screen. “It’s your turn.”

Mark scores a 0.91. It’s going to be the last time he scores a 0.91.

“Not bad for your first try,” Donghyuck tells him. 

“It's pretty bad," Mark says. He shrugs, looking at his data points scattered embarrassingly far off the standard curve. “It’s cool though, I’ll just have to—next time. Like, once I’ve gotten the hang of it, the pipetting. _I’m_ gonna win.”

“That’s the spirit,” Renjun says approvingly. “You won’t, but positive thinking is always good!”

“Hey,” Mark says, twisting around in his chair. “How come Jaemin and Jeno are never in the lab?”

After the first week or so, the two of them stopped running Gradiflow cycles and Mark hasn’t really seen either of them in a while. Sometimes at lunch, or at the end of the day when everyone’s packing up, but not in the main labspace anymore.

Renjun shrugs, looking supremely unconcerned. “That’s their business,” he says. 

“They get to do fun protein-counting activities in the back room that don’t involve six-hour runs,” Donghyuck says, with alarmingly placed emphasis. 

Mark opens his mouth to ask if Donghyuck meant it to sound like that, then decides there’s really no need. “Right.”

“The less you know, the better,” Donghyuck says, gleeful innuendo dripping off each word.

“_Right_,” Mark says again.

Donghyuck sneezes into the crook of his arm. Immediately Renjun scoots to the end of the bench. “If you get me sick before Worlds auditions I’ll come back to haunt you after I die,” Renjun warns.

“Thank you for your sympathy. When I get rabies,” Donghyuck informs Renjun, “I will make sure to personally spit in your mouth.”

“_When_ you get rabies?” Mark interjects.

“We’re in a microbiology lab,” Donghyuck says. “Anything could happen.”

“Right,” Mark says, for the third time. He eyes the fume hood with increased trepidation.

“Excuse me,” comes a soft voice from the entrance, blessedly cutting the conversation off before it takes too distressing a turn. As one, the three of them turn to look at the girl in plainclothes standing politely on the other side of the lab entry line.

“Hi?” Mark offers.

“Hi!” the girl chirps, pushing her hair over her shoulder. “I’m Yiren, from Junhui’s lab upstairs! Do you guys have any spare whiteboard markers? We’ve run out…”

Renjun, who’d basically leapt to his feet the second Dr Wen’s name was invoked, says with more enthusiasm than Mark’s seen from him in the entire length of their acquaintanceship thus far, “Sure! We have a bunch in the back room, I’ll go grab a few—” 

“Oh, you don’t need to do that, just tell me which door and I can get them myself—”

“It’s no problem, really—” 

“Just go,” Donghyuck sighs, waving a hand at the two of them and breaking up the customer service voice standoff unfolding. Yiren blinks, then offers Renjun an uncertain smile, gestures for him to lead the way. Turning so that Yiren can’t see, Renjun shoots Donghyuck the evil eye before courteously leading Yiren out of the room. 

“Starting to think Renjun doesn’t like me… all these excuses he comes up with to leave the room when I'm in it,” Donghyuck says sadly. “Kinda heartbreaking.”

“You were literally the one who told him to go,” Mark says. “Also aren’t you guys self-declared arch enemies anyway?”

“Sometimes,” Donghyuck says solemnly, “I say things,” and Mark waits for the second half of the sentence, but after a while it becomes clear Donghyuck has lost interest in continuing this line of thought.

“And?” Mark prompts.

“And what?”

“You say things, and…”

“And they are said by me.”

“And—okay, you’re just fucking with me.”

“Sorry,” Donghyuck says, grinning and not sounding particularly apologetic. “You just make it so easy.”

Mark kicks at his shin, dangling against the stool leg. Donghyuck kicks back, then stills, turning his head in the direction of the back room as if he's heard or maybe psychically sensed something Mark can't. Sure enough, seconds later Renjun reemerges into the lab unaccompanied.

“Well?” Donghyuck demands. “How did things go?”

Renjun looks at him evenly. “What do you mean, _how did things go_? I lent Yiren from the Pleiades Lab some whiteboard markers.”

“No way is that it,” Donghyuck says. “And? What else?”

“Please just tell him,” Mark says. “Or we’ll be here all day.”

“You know me so well,” Donghyuck declares, pressing a hand to his chest. “You heard him, Renjun. Spill.”

Renjun exhales loudly through his nose. “Yiren’s supervisor is best friends with Dr Meiqi Meng, who’s giving a talk on quasars next week at a Pleiades conference. Yiren invited me to come with.”

Donghyuck whistles. “Sexy first date ideas!”

“In a _friendly_ way,” Renjun says severely, but there’s an upturn to his lips that says otherwise.

“That sounds fun, though,” Mark says. “You like space, right?”

“Oh, we are really in for it now,” Donghyuck mutters, but it’s fond.

“Space is really cool!” Renjun says, eyes suddenly alight. “I like that there’s so much we don’t know… the universe is so big. Anything could be out there.”

Anything could be out there. And its reverse: Mark could’ve been anywhere in the universe but here he is, sitting in a bright clean lab, listening to Renjun’s theories on extraterrestrial life. Donghyuck shifts in his chair. The light hits the rim of Donghyuck’s safety glasses, casts a shine over his face. He looks different with his face upturned. They spend pretty much the entirety of the day indoors, but Mark thinks he wants to properly see what Donghyuck looks like in the sun.

Just before lunch, Renjun ambushes him at the water fountain. “Can you come with me for a moment,” Renjun says, placing an imperious hand on Mark’s forearm. The lack of a question mark is clear: Mark evidently has no say in the matter. 

_Rooftop,_ Donghyuck mouths at him over Renjun’s shoulder, waggling his eyebrows suggestively. Mark pulls a face at him, which is about all he has time to do before Renjun is tugging him out of the room and off to a set of emergency exit doors.

The mindless task of trailing after Renjun up the endlessly spiralling fire escape staircases leaves Mark with enough vacant brainspace to mull over the likelihood that Renjun is about to ritually sacrifice him on the rooftop and dispose of his body in peace. Renjun seems to enjoy efficiency, after all.

They emerge into a gust of wind that slaps Mark directly in the face, nearly shoving him back down the stairs. He blinks away the sting to his eyes, squints out at the ugly and nondescript concrete, tries to will away the fear of heights he’s just spontaneously developed. Renjun, unfazed, beelines for the edge of the roof; Mark eyes a suspiciously shaped maroon stain on the ground and gives it a wide berth on his way to the railing.

“I like it up here,” Renjun says, as Mark approaches. “I can hear myself think.”

Between the wind, the air conditioning unit working overtime and the lulling sounds of city traffic drifting up from ground level Renjun actually needs to raise his voice to be heard. “Haha?” Mark says uncertainly. “Um… was there something you wanted to talk to me about?”

“No,” Renjun says serenely. “But I think there’s something _you_ want to talk to _me_ about.”

“There is?”

"Yes," Renjun says. “Starts with a D, ends with a k. Both possible answers are actually the same answer.” 

“Oh,” Mark says. Then comprehension dawns. “_Ohhh._ Ahaha. Um… I do?”

Renjun does not look impressed. “Must I hold your hand through this?”

“Can I get a vowel?” 

“What do you think about Donghyuck?"

Mark parries with, "What do _you _think about Donghyuck?"

"Donghyuck is my best friend," Renjun says. "Your turn."

Not expecting the directness, Mark flounders for a moment. “I—is this, like, is this a, what’s it called, a shovel talk?”

Now Renjun’s off-balance. “A what?”

“You know, where you threaten to kill me if I don’t, like, treat Donghyuck properly, not that that’s going to be a problem, because we’re not… you know. Like that. Or anything. Okay, good talk!” Mark spins sharply on his heel to escape back down the stairs. 

Renjun stops him with a hand on his shoulder. When Mark turns around again Renjun is smiling, a surprisingly gentle expression. “You said it,” he says. “Not me. You should think about what that means.”

“You’re actually really nice, aren’t you?” Mark says. “Like, you care a lot about Donghyuck.”

Renjun’s expression tanks quicker than a stock market index after an inverted yield curve (Mark’s Corporate Finance final assignment is still weighing on his mind). “I would never care about Donghyuck,” he says sourly, even though he just admitted to best-friendship two minutes ago. 

“Of course,” Mark agrees, Jaemin’s so-called free advice flashing through his head like ticker tape. Clearly cheered by the concession, Renjun brightens again. 

“Well,” Renjun says. “Just remember that at any time I could have thrown you off the roof. But I didn’t.”

This is not even remotely threatening. Actually it's kind of sweet. Mark must really be acclimatising. 

“I spy with my little eye something beginning with—”

“Centrifuge.”

“Damn, I didn’t even say what letter, how’d you guess so fast?”

Renjun stops swivelling his stool from side to side and fixes Donghyuck with a baleful eye. “Your last three turns have all been _centrifuge._”

“Well,” Donghyuck says, gesturing at the row of centrifuges on the lab bench beside him, “I don’t exactly have a great range of scenery to choose from.”

“You could mix it up,” Mark suggests. “Throw in a multipipette or two?”

“Or we could stop playing I Spy,” Renjun says. “That’s also an option, just so you’re both aware.”

“It’s a team-building exercise,” Donghyuck says. “Raises morale.”

“In _what_ way.”

Donghyuck doesn’t bother replying to this. The majority of what Donghyuck and Renjun say to each other, Mark has come to realise, goes blithely disregarded, half the threads of their conversations left severed and hanging. What a strange way to weave a friendship. But clearly it works, and more than that it works _well_. From the look of things it seems that, even though they communicate largely in insults and threats with oddly affectionate undertones, in the terrifyingly likely possibility that Renjun would ever find himself needing to hide a body, he’d have Donghyuck on speed dial, and vice versa.

Mark wouldn’t say he’s jealous. Maybe just wistful. Closeness that can’t be approximated even with the benefit of a margin of error, room for interpretation. That doesn’t mean he won’t try for it, though. Zeroing in on the mismatch and working it over until it lines up.

“I spy with my little eye—” 

Renjun groans and spins his stool around to face the bench so he can slump forward and bury his head in his forearms.

“—something beginning with _m_.”

“Multipipette,” Mark says.

“Wrong!” Donghyuck announces gleefully. 

Renjun lifts his head and cranes his neck to look back up at Donghyuck. “My will to live,” Renjun says. “Oh, wait, that can’t be right, it’s nowhere to be seen.”

“Good guess, but no,” Donghyuck says. “See? This is exactly why we need morale-raising activities.”

Renjun rolls his eyes like he’s trying to make a case for the act to be considered an Olympic sport. “Alright, I’m going to go find Jaemin and Jeno,” he says. “And see if they need any help with… counting proteins.”

“Disgusting,” Donghyuck hisses. “Have you no regard for lab safety protocols? Did you learn nothing from the twenty-seven-slide presentation Taeyong sat us through?” Donghyuck turns to Mark and adds, “Consider yourself lucky you got Johnny and then me for your orientation.” 

“I live and breathe hygiene,” Renjun says primly, standing up and sliding his stool back under the table. “And at least twenty of those slides were specifically directed at you, _I’ve_ never been the cause of a sitewide evacuation.”

“If I need to pull the emergency shower on you I can and I will,” Donghyuck calls at Renjun’s retreating back. This, too, Renjun ignores magnificently as he rounds the corner and disappears.

“They… are actually counting proteins, right?” Mark says, after a moment. “Like, that’s not a euphemism for anything?”

“Oh, yeah,” Donghyuck says. “Who do you think we are? Here at Neo Biologics we take proper lab etiquette very seriously.”

“Right, of course,” Mark says. “Because remember how in our first conversation ever you told me about how you stole a pipette—”

“At _Neo Biologics,_” Donghyuck interrupts loudly, “we put safety and hygiene first. What happens at Culture Biotech is irrelevant. Inadmissible evidence.”

Mark swallows down a laugh. He sets his elbows back on the bench. “Hey, so what was the word?”

“Hmm?”

“Your last I Spy word. The _m_ one. What was it?”

Donghyuck grins, a bright flash of teeth. There’s a little chip on one of his incisors Mark hadn’t noticed before. All of a sudden he can’t stop noticing. Teeth, the corners of his mouth, laddering up the moles on his cheek to the curve of his eyes. 

“Mark Lee,” Donghyuck says. “I see you.”

The steady drip of liquid into the collecting test tube is strangely soothing to watch. Mark’s discovered this in the absence of anything better to do and almost wishes he’d found it out earlier, it’s like meditation without the meditation, or something. Clearly unsatisfied with Mark’s choice of pastime, Donghyuck has wandered over to the far end of the lab to shuffle through some papers.

There’s a hiss, quiet. Mark glances up. Donghyuck’s shaking his hand out, looking more offended than pained, and moves towards the sink. Mark goes to join him.

“Ugh,” Donghyuck says. He grimaces, examining his finger with a bored expression. It doesn’t look too bad to Mark, a long thin line welling up with red beads. Probably hurts like fuck, though. Things close to the surface always do.

“Hey,” Mark says. “Do you want me to help you with that?”

“It’s barely a paper cut,” Donghyuck scoffs, turning the tap on with his uninjured hand and rinsing the scrape out. He pats it dry with a paper towel and then imperiously thrusts his hand at Mark.

“Barely a paper cut, huh,” Mark says, reaching for the first aid kit under the sink. He peels a band-aid halfway and loops it around Donghyuck’s finger.

“_Ow_—fuck, watch it, if you get my finger infected and it needs to be amputated I have a very good lawyer and you’ll be hearing from him—do you even know how to do first aid?” 

“Of course I know how to do first aid,” Mark says. “You know, DRSABCD, RICE, all that stuff, I’m so on top of it.” He lifts the plastic backing off the band-aid the rest of the way, sealing it shut.

“RICER,” Donghyuck says, but he doesn’t draw his hand back. “It’s RICER.”

“No it’s not,” Mark says. “Rest, ice, uhh… compression, elevation… what’s the last _r_ even supposed to be?”

Donghyuck pauses. “Okay, I may not be able to remember right now but that doesn’t mean I’m wrong. It’s like... reversal. Something like that.”

“How is it supposed to be _reversal, _there’s nothing to reverse!”

“The injury, duh,” Donghyuck says, rolling his eyes.

“Literally _how_,” Mark says. “Magic healing powers don’t exist?”

“You’re still holding my hand,” Donghyuck points out. 

Mark drops Donghyuck’s hand like he’s been burnt. “Hey—wait, that was a deflection!” he shouts. “You just don’t want to admit you’re wrong!”

Donghyuck laughs. “You’re cute,” he says, in a tone that’s total unfiltered delight. 

There’s an expanding air bubble trapped underneath Mark’s sternum. Mark thinks he might die. He’s heard about what happens to scuba divers who resurface too quickly, the bloodstream bubbling, bursting open. That sense of vertigo rising up, what should be lifegiving becoming fatal instead. 

But he can’t die here. It would probably make Taeyong very stressed and if there’s one thing Mark is pretty sure Taeyong doesn’t need more of in his life, it’s stress. Short of putting himself in a centrifuge, he goes for the next best option and deflates the feeling as best as he can.

“Back on my first day, all those signs with arrows on them,” Mark starts.

“I made them,” Donghyuck says. “I was worried! What if the new kid got lost on their way from the reception to the lab… those three hundred metres of hallway in between are treacherous waters, you know.”

And isn’t that just Donghyuck, the arrow signs, the drinks, the micropipettes, real kindness papered over with mischief. Reams of plausible deniability. Reams of heart.

“I actually thought it was pretty nice of you,” Mark says. “Or—yeah, wait, no, I was like…” On second thought, it’s probably not a great idea to divulge that he’d been momentarily concerned about the Neo Biologics team’s ability to navigate its own labspace. “Yeah, never mind.”

“What, did you think those signs were for _us_?”

Mark laughs. “How did you know?” 

“Mark Lee,” Donghyuck says gravely, except there’s a very real weight to the words underneath the mock seriousness, one that lodges like a bullet in the base of Mark’s throat, tells him _pay attention,_ tells him _remember. _A corona of fearlessness in Donghyuck’s eyes. “I—” 

What Donghyuck is Mark will never find out, because at that precise moment the Gradiflow beside him explodes.

“It wasn’t me!” is the first thing out of Donghyuck’s mouth when Taeyong rushes into the lab, probably alerted to the state of affairs by all the shrieking.

From the outside, the rogue Gradiflow doesn’t actually look too bad, a few wisps of smoke curling off out of the vents, a huge crack running down one side of the machine, but otherwise it remains largely intact. Operating on sheer instinct Mark had yanked the plug out the moment the firecracker noises started but he’d knocked over the test tubes in the process, leaving the Gradiflow husk to sadly drip plasma and buffer all over the bench before Donghyuck kicked into gear and grabbed a plastic container to catch the leaks.

Now, Donghyuck starts blotting up the fluid seeping out from under the Gradiflow with a handful of paper towels swiped from the sink, and Mark goes to help him, crouching down to pat the floor where the buffer’s pooled in a sad cloudy puddle beneath the bench dry as well.

“Don’t worry about it, don’t worry about it,” Taeyong is saying, like the repetition will somehow erase the feeling of worry itself from existence, “don’t worry about it—um, it’s fine, it was an old machine anyway, probably due for a replacement… did any of the plasma get on you?” Donghyuck shakes his head. “That’s fine then, don’t worry… why don’t you guys wait outside the lab while we get this cleaned up?”

So Mark and Donghyuck evacuate the premises. It feels weird standing in the red zone without starting the cleanup process so, in the absence of anything else to do, Mark washes his hands, twice. Moments later Renjun flies in the door, taking Donghyuck’s face in his hands and scrutinising him for any sign of damage. Donghyuck grumbles but lets him have his way.

After briskly ascertaining that Donghyuck made it out alive and unscathed, Renjun promptly returns to his favoured hobby of antagonising him. “I bet you still did it somehow,” Renjun says darkly. “The Gradiflow is a sensitive instrument, I bet it sensed your malevolent energy and overloaded and that’s what made it blow up.”

“Please,” Donghyuck sneers. “If that was true every Gradiflow within a five-metre radius of you would’ve melted into a pile of plastic goo _months_ ago.”

“My soul is pure,” Renjun says, with the kind of absolute serenity that could only be borne from an utterly righteous and possibly misplaced self-conviction.

“Pure my _ass,_” Donghyuck mutters. “I know you have designs on my best friend’s virtue, you homewrecking fiend.”

“It isn’t homewrecking if you’re invited in,” Renjun says.

“Like a vampire? So you’re gonna suck the life out of him? That’s what it is?”

At some point over the past month or so the sound of Renjun and Donghyuck bickering had lost its initial edge and turned into soothing ambient noise, like ASMR or those rain playlists that are supposed to help you fall asleep even though they’ve never actually worked on him, which Mark supposes just goes to show the power of exposure therapy. Or maybe more like the speed at which humans develop essential survival mechanisms. But whether or not he’s been Stockholmed into it, he’s used to it now. Endeared to it, even. 

Something occurs to Mark. “Hey, how’d you even find out so quickly?” he asks.

“Wouldn’t you like to know,” Renjun says shortly. “I’ll go and tell Jeno and Jaemin you’re both still alive, try not to cause any other explosions while I’m away. The cycle’s nearly over.”

“That was so ominous and for what? _The cycle’s nearly over_, why would you say it like that—and he’s gone. Bye, Renjun!” 

“How much longer do we actually have, anyway?” Mark says.

Donghyuck shrugs. “On this earth? Hopefully forever, or at least a very long time. Until the thirty minutes are up? Like… another five minutes.”

There’s a brief lapse into silence. It’s strange, seeing Donghyuck with nothing to say, and Mark feels the urge to stopper the quiet. “So,” Mark says. “That was a real shock, huh.”

“God, I nearly died of a heart attack,” Donghyuck says fervently. “I know Taeyong said it was fine but I’m still… I kinda feel bad about it, I won’t lie.”

“There’s no way you could have seen it coming,” Mark says firmly. “It was just bad luck. Though I guess you’re probably not used to what that feels like.”

“I do usually live a charmed life,” Donghyuck agrees, flashing him a toothy smile that burrows right under Mark’s ribs.

That’s something he’s noticed as of late, how he’ll feel it like a physical reaction when Donghyuck laughs or tosses off something witty or gets that look of intensity when he’s really focusing on a task. Mark’s head always feels a little like it’s gone a few rounds in the centrifuge, vertigo catching up to him, but that’s part of the thrill. He likes challenge, something to work up to; likes the bright unpredictability like a sheer curtain over something softer, and that’s why he keeps rising to the bait every time. He likes the interplay between knowing and not knowing. And he likes Donghyuck.

The realisation comes down like a stage curtain, mimicking the heartstopping swoop of a guillotine without its attendant absolute finality. It’s an incredibly unromantic setting to have this kind of epiphany in, what with the wall of hanging lab coats to his left and the emergency shower to his right and the fact that a machine basically puked its guts out over them five minutes ago. Standing at the threshold of the room, not inside the laboratory but not really out of its reach either, the ugly fluorescent lighting banishing all trace of shadow, Mark gauges the distance between himself and where Donghyuck stands, or more accurately slouches, hands shoved disconsolately in the pockets of his lab coat, safety glasses perched atop his head. That little length of floor, crossable in seconds. 

“Hey,” Mark says, feeling reckless.

Opening, lifting, beginning; sometimes the only way to figure something out is by doing it.

Donghyuck pivots 45 degrees to face him. “Hmm?” 

“We’re on the other side of the boundary,” Mark says, toeing at the thick black line delineating the entry into the laboratory zone. He takes off his own safety glasses and tucks them into the pocket of his lab coat.

Donghyuck blinks at him, slow sweep of eyelashes over the crest of his cheek. “Okay, and?”

“So we’re not in the lab anymore,” Mark says. 

He takes a step closer, watches Donghyuck’s gaze sharpen in comprehension, but of course Donghyuck isn’t going to make it easy for him. Mark has to fight off the answering smile. 

“And what are you gonna do about it?” Donghyuck challenges. The words have the lilt of a taunt but not the bite. An anticipatory glitter to his eyes.

It’s easy to lean in, cup a hand around the nape of Donghyuck’s neck, draw their mouths together. Once Mark’s done the work closing the gap Donghyuck twines his arms around Mark’s shoulders and responds so sweetly it throws Mark off-kilter for a moment, floundering as Donghyuck drops all motions of fronting or resistance. Donghyuck’s safety glasses clatter to the floor, which Mark ignores. It’s awkward, and then it isn’t, Donghyuck’s mouth opening up under his, and he lets his eyes slip shut. 

From somewhere behind them there’s the sound of a throat being cleared. Reluctantly Mark pulls back to see Renjun standing a polite, pointed distance away with his arms crossed, but he’s looking kind of fondly misty-eyed, so Mark counts that as a win.

“Not to interrupt or anything—”

“You are absolutely interrupting,” Donghyuck says, scowling as he grabs Mark’s hand as if to make up for the lost point of contact.

“—but you’re blocking the doorway,” Renjun says. “Can you guys let me in and then you can go back to propagating unsafe lab practices or whatever.”

“We’re not actually _in_ the lab,” Mark says, pointing at the boundary line with his free hand. 

Renjun pauses. He looks at the line, then up at Mark. Then, like it’s surprising even himself, he smiles. “So you aren’t,” he says. 

“A concession from Renjun Huang, is the world ending,” Donghyuck mutters under his breath, just loud enough for Renjun to also hear the words. But he pulls Mark to the side to let Renjun past, upon which he’s immediately shooed out of the lab again by a hovering Taeyong acting as a human cordon while some lab technicians look over the wreckage.

“Anyway, I can’t believe it took my experiment literally self-destructing to make you get a clue,” Donghyuck grumbles. “That’s four good hours of data down the drain. Now I have to spend an entire six more hours in the lab doing a replacement run. I should’ve just sabotaged Renjun’s Gradiflow instead.” 

“Thanks for sparing mine,” Mark tells him, squeezing his hand.

“Never let it be said I wasn’t merciful to the new kid,” Donghyuck says. “I'm basically a saint. I know, I know.”

As soon as the broken Gradiflow is cleared off the bench it’s time up for the remaining two machines, so it’s left to Mark and Renjun to take samples and set up for the next cycle while Donghyuck sits on a stool and kicks his legs, pretending to sulk. He passes Mark the thermometer when Renjun puts his hand out for it and cackles when Renjun scowls and swipes it out of Mark’s grasp. 

The lab must go on, and all that. But it’s not so bad, the routine, even the interruptions, bound to happen with an intern team like this. It’s all part of the learning curve. Onwards and upwards. Donghyuck grins at him across the aisle, smile like something contained in glass, the explosive reaction held off just for the moment. So much to look forward to, the rest of the summer opening up ahead of them. Mark smiles back.

**Author's Note:**

> yes 'the market's absolutely fully capable' is what i originally heard the lyric as... no i did not question why mark lee was commenting on the state of the economy in mad city
> 
> i'm on twitter [@juncheolsoo](https://twitter.com/juncheolsoo) / cc [@inheritance](https://curiouscat.me/inheritance) ♡


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